The gear pump has been known as a pump installed in a vehicle, a construction machinery, or a machinery or device such as a robot as a hydraulic pressure source of an actuator. The gear pump has such a feature that pressure pulsations caused by pump operation are suppressed, and operation sound becomes smaller because the discharge amount of the pump per revolution of a drive shaft can be reduced as compared with a piston pump having the same size.
An example of a conventional gear pump is disclosed in Patent Literatures 1 and 2.
A gear pump disclosed in Patent Literature 1 includes a pump assembly having two gears, two side plates that come in narrow contact with the two gears, and a seal block that seals addendums of the gears, and a case that houses the pump assembly. The pump assembly rotates due to a reaction moment caused when a drive shaft rotationally drives gears, but a leading end of the seal block comes in contact with an inner wall of the case to stop the rotation of the pump assembly. The pump assembly is positionally fixed in this way, and positioned.
A gear pump disclosed in Patent Literature 2 includes a pump assembly having two gears and a seal block, and a case that houses the pump assembly, and the rotation of the pump assembly about a drive shaft stops due to a rotation stopper also serving as a suction port. The pump assembly is positionally fixed in this way, and positioned.